This invention relates to an inhaler for dispensing an aerosol from a container. In particular, the invention relates to an inhaler for dispensing medication from a metered dose canister with minimal effort and convenience to the user, and while preventing undesired rates of inhalation of the dispensed medication.
Inhalers are commonly used to dispense an aerosol for treatment, or alleviation of the effects of respiratory complaints, such as asthma. One of the most convenient choices of treatment of respiratory complaints has been the inhalation of medicament from a drug solution or suspension in a metered dosed pressurized inhaler (MDI).
Standard metered dosage inhalers have effectively produced an aerosol of medication in a predetermined dosage for delivery to the lungs. However, awkward dispensing mechanisms as well as inefficient delivery systems decrease the likelihood that the medication effectively reaches the users lungs. Known inhalation devices typically comprise a tubular housing or sleeve in which a pressurized aerosol container is located and a mouthpiece or nozzle leading out of the tubular housing. In use, the aerosol container is placed into the housing, which is then held by the patient in a more or less upright position, and the mouthpiece or nozzle of the inhalation device is placed in the mouth or nostril of the patient. The patient inhales through either the mouthpiece or nozzle while simultaneously releasing the medication from the aerosol container. With all such devices, the patient releases the medication either manually by pressing on a bottom surface of the aerosol container, or using an actuator that exerts a force on the bottom surface of the aerosol container.
The most significant problem associated with such inhalation devices has been the difficulty for many patients to coordinate the manual release of the medication with the initiation of inspiratory effort. Indeed, many people not afflicted with asthma, bronchitis, emphysema, or other respiratory difficulties have demonstrated that they are unable to coordinate these tasks properly. Patients suffering from the distress of broncho-constriction have much greater difficulty. Patients such as children, geriatrics, arthritics, the physically challenged and the infirm also have great difficulty in holding the inhalation device to the mouth or nostril while depressing the aerosol container. As a result, a large percentage of inhaler users may fail to inhale the proper dosage of medicament. Thus, there are many groups of patients who could receive an increased benefit from aerosol medicaments if an inhaler were available that minimized the problem of coordinating the release of the medicament with inhalation.
As mentioned above, some prior art inhalers incorporate an actuator that exerts a force on the bottom surface of the container to assist the release of the medication. Examples of these inhalers are found in U.S. Pat. No. 4,678,106 to Newell, and U.S. Pat. No. 4,834,083 to Byram. In these prior art inhalers, the shape of the inhaler is dependent upon the length of the container. This is problematic in that it prohibits patients from using one inhaler regardless of the length or manufacturer of the canister. Thus, patients who take more than one medication would need a number of different sized inhalers designed to fit each specific canister.
Another known problem with prior art inhalers is the difficulty in achieving optimal deposition of medication. Prior art metered dose inhalers, upon actuation, dispense short bursts of medication traveling at a relatively high discharge velocity. However, it is known in the art that a slow and deep inhalation coordinated with activation of the inhaler increases the amount of medication received in the lungs. Much of the prior art has attempted to solve this problem by providing various enlarged chambers that receive the discharge from the inhaler and hold it therein until withdrawn by the user. The ACE(copyright) aerosol cloud enhancer, U.S. Pat. No. 4,926,852 issued to Zoltan, et al., U.S. Pat. No. 5,203,323 issued to Tritle, U.S. Pat. No. 5,042,467 issued to Foley and U.S. Pat. No. 4,470,412 issued to Nowacki, et al. are each examples of expansion chambers. However, providing a chamber alone does not avoid ineffective inhalation.
Some of these prior art inhalers, such as the ACE(copyright) aerosol cloud enhancer, have included a coaching whistle at the end of the chamber that sounds if a patient inhales above a desired inhalation rate. However, patients who cannot hear the whistle or choose to ignore the whistle will suffer from ineffective administration of the medication. Furthermore, the coaching whistle has an unobstructed opening through which the medication can quickly and easily escape from the chamber either by exhalation of the patient or by the natural flow of the medication.
A need exists for an inhaler that requires minimal strength to administer medication, that is capable of administering medications in containers of a variety of volumes, and capable of containing the medication in the chamber while prohibiting rapid inhalation. The present invention addresses these needs by providing an inhaler with a unique activation system to reduce the effort associated with the delivery of inhaled medication from a variety of containers, and a flow restrictive valve to regulate the rate of inhalation of the medication, thereby maintaining a therapeutic inspiratory flow.
The invention relates to an inhaler for releasing an aerosol from a container. The container has a lip and an outlet normally sealed by a stem. The stem is movable relative to the lip. The inhaler has an elongate body, and an actuator pivotably attached to the elongate body. The elongate body has a chamber, a stem block, a dispensing nozzle and a flow restrictive valve. The chamber has an opening at one end and, in a preferred embodiment, the opening is adapted to receive a mouthpiece or a mask attachment. The stem block has a socket adapted to receive the container stem. The dispensing nozzle is adjacent to the stem block and provides communication between the socket and the chamber. The dispensing nozzle is also adapted to direct a discharge of the aerosol, when actuated, from the container stem into the chamber. The flow restrictive valve is in open communication with the chamber and responsive to a change in fluid pressure, typically resulting from inhalation and exhalation of the user of the inhaler. The actuator is pivotably attached to the elongate body and has an opening adapted to receive the lip of the container. The actuator also has a detent for forming a removable connection between the lip of the container and the actuator. The actuator opening is located substantially directly above the socket.
In a preferred embodiment, the chamber has a door pivotably attached to the chamber. The door provides access to the inside of the chamber to store the canister and mouthpiece. In another embodiment, the dispensing nozzle is adapted to direct a discharge of the aerosol toward the opening of the chamber. The dispensing nozzle shape, preferably is a tee-bar shape, an oval, conical or cylindrical. In one embodiment, the chamber is elliptically shaped and the dispensing nozzle is further adapted to shape the discharge of the aerosol into a flattened plume.
The flow restrictive valve may comprise a leaf valve, a flexible member, or a movable cylinder. The flow restrictive valve is responsive to a change in fluid pressure. The flow restriction valve assists in controlling the flow of fluid and has components that are moveable from a substantially open position to a substantially closed position at about predetermined maximum inhaled flow rate. A leaf valve stop may be incorporated into the flow restrictive valve to prohibit the leaf valve, flexible member, or moveable cylinder from closing at the predetermined maximum inhaled flow rate. In one embodiment, if the user exhales into the chamber, the valve will substantially close and cause a redirection of fluid through a fluid relief hole in the mouthpiece wall.